1. Field of Invention
The present invention relates to an electrooptic device and an electronic apparatus having many electrical elements formed on a substrate that supports an electrooptic material. The invention also relates to a method for making such an electrooptic device. Specifically, the invention relates to examining electrical characteristics of the electrical devices formed on the substrate.
2. Description of Related Art
In related art electrooptic devices, such as liquid crystal devices and organic electroluminescent devices, many switching elements are formed on a substrate supporting an electrooptic material.
An example of such an electrooptic device is an active matrix liquid crystal device employing thin film transistors, hereinafter “TFTs,” as the pixel switching elements. In making the device, as shown in FIG. 20, components of a plurality of TFT array substrates 10 are formed on a large substrate 10e, and the large substrate 10e is cut along cutting lines 10f so as to prepare individual TFT array substrates 10 used in liquid crystal devices.
The regions sandwiched by the cutting lines 10f are generally used in the related art as inspection regions 10g to inspect pixel-switching TFTs 30 formed in a matrix inside pixel regions 10a of the TFT array substrates 10 and to inspect driving-circuit TFTs (not shown) that constitute driving circuits 101 and 104, as shown in FIG. 21.
In other words, the pixel-switching TFT 30 is formed in each of the pixels arranged in a matrix on each TFT array substrate 10. When the TFT array substrate 10 is of an internal driving circuit type, the driving circuits 101 and 104 are constituted from TFTs (not shown). In the related art, the process for forming these TFTs is also used to form an inspection TFT 30g′ functioning as an inspection pattern, a first inspection pad 31g′ electrically connected with a drain region of the inspection TFT 30g′, a second inspection pad 32g′ electrically connected with a source region of the inspection TFT 30g′, and a third inspection pad 33g′ electrically connected with a gate electrode of the inspection TFT 30g′ within the inspection region 10g. These processes are performed onto the large substrate 10e shown in FIG. 20, and one inspection TFT 30g′ is formed in the inspection region 10g near one TFT array substrate 10 (one-to-one correspondence).
The electrical characteristics of the inspection TFTs 30g′ are examined by bringing inspection terminals into contact with the inspection pads 31g′,32g′, and 33g′ while they are mounted on the large substrate 10e. If the electrical characteristics of the inspection TFT 30g′ are satisfactory, those of the pixel-switching TFTs 30 formed in the corresponding TFT array substrate 10 are assumed to be satisfactory, and the TFT array substrate 10 is assembled into a liquid crystal device. On the other hand, if the inspection TFT 30g′ is found to be defective, the pixel-switching TFTs 30 formed in the corresponding TFT array substrate 10 are assumed to be defective, and this TFT array substrate 10 is discarded. As a result, the yield can practically be increased. Moreover, the position in the large substrate 10e that is likely to suffer from defects can be detected, and the results can be easily reflected in the manufacturing process.